Silica aerogel has a chemical formula expressed as SiO2.nH2O, high porosity of 90% to 99.9%, and a pore size of 1 nm to 100 nm. The silica aerogel may be a material a high specific surface area with super porosity of 600 m2/g.
Since silica aerogel has a nanoporous structure and a very large surface area, the silica aerogel may have very excellent water and alcohol absorption ability and thus be used as very superior dehumidifying agent and utilized as an ultra light and super thermal insulation material, a catalyst carrier, and a super insulation material.
In spite of a vast range of application, the silica aerogel is extremely limited in use.
The core technology in a process for preparing the silica aerogel is a drying process technology that is capable of drying the wet gel without being contracted while maintaining a structure of the silica wet gel as it is. A representative drying method is a super critical drying process. However, since the super critical drying process has many limitations in terms of economical efficiency and continuity because of using an autoclave that has high production costs and high risks due to a high pressure and is impossible to continuously operate. In addition, there are disadvantages that not only risk factors are comprised in the manufacturing process, but also the manufacturing costs are high due to the complicated manufacturing process.
Although there are commercially available techniques for drying the silica wet gel at a normal pressure in preparation for such disadvantages, there is a disadvantage in that a large amount of liquid exists inside and outside the silica wet gel, and thus, large drying costs are required for drying the silica wet gel.
Also, since many raw materials are used for preparing the silica aerogel, it is urgently required to develop a technique for reusing the raw materials. For this, many suggestions with respect to techniques and operating conditions for separation purification so as to reuse the used raw materials may also be necessary.